This winter will probably be colder than normal for much of the northern United States, although a repeat of the worst of last winter's East Coast snowstorms is unlikely, according to forecasters.
A cooling in the Pacific Ocean known as La Nina is predicted to return this year, joined by another season of frigid Arctic blasts caused by pressure differentials over the North Pole and northern Atlantic Ocean.
"We're looking at a cold start to the winter with maybe a mild finish," said Matt Rogers, president of Commodity Weather Group in Bethesda, Md.
Forecasters are predicting the coldest weather from the Great Plains to the Great Lakes, along with heavy snows across the northern tier.
The coming winter may be colder than both the 30- and 10-year averages, said Travis Hartman, a meteorologist at MDA EarthSat Weather in Gaithersburg, Md. Nov. 1 to March 31 will probably be 7 percent colder than the 10-year norm and 1.3 percent colder than last year, Rogers said.
New York City may be hit by several snowstorms, according to Hartman. But he doesn't expect a repeat of the past two years, when record snows fell in Central Park and some city streets were unplowed for days.
The upper Great Plains, Great Lakes and Midwest may see another year of heavy snow, he said. When the snow pack from last winter melted, it caused record flooding along the Ohio, Mississippi and Missouri rivers as far south as Louisiana.
Hartman said that depending on how fast and when the snow melts, more flooding may be in store in the first half of 2012.
The coldest area may be the northern Great Plains, Midwest and Great Lakes region, said Paul Pastelok, a meteorologist at AccuWeather Inc. in State College, Pa. The Northeast probably won't be as cold or snowy as last year, he said.
The U.S. Climate Prediction Center's latest forecast for January to March 2012 calls for most of the country to have seasonal temperatures, with about a 50 percent chance the upper Plains and Great Lakes will be below normal.
Rogers said he is confident the start of winter will be colder because when there are back-to-back La Ninas, as in 2010 and 2011, the second one tends to bring lower temperatures to the U.S.
On average, La Ninas occur every three to five years and last from nine to 12 months. Last year's La Nina was a contributor to record flooding in Australia, the persistent Texas drought and an above-average Atlantic hurricane season.
Forecasters are also watching to see if low pressure develops over the North Pole, a pattern called the negative phase of the Arctic Oscillation. When this happens, cold air is pushed down into the temperate regions of North America, Europe and Asia and the pole is warmer than normal.
It can also cause blocks that disrupt the normal flow of the atmosphere. If the blocking occurs off the East Coast, then New York, New England and the mid-Atlantic may see a lot of snow, Pastelok said.